Rep. Adam Schiff, D-Calif, the chairman of the House Intelligence Committee, subpoenaed acting Director of National Intelligence Joseph Maguire on Friday, claiming Maguire is unlawfully withholding a whistleblower complaint from Congress, possibly to protect the president or top administration officials.

In a statement, Schiff said that Maguire would be required to testify on Thursday, Sept. 19, unless he complies with the subpoena. The lawmaker did not detail the subject of the complaint, but noted that the intelligence community’s inspector general (IC IG) determined it to be “credible and of ‘urgent concern.'”

“A Director of National Intelligence has never prevented a properly submitted whistleblower complaint that the IC IG determined to be credible and urgent from being provided to the congressional intelligence committees. Never,” Schiff said. “This raises serious concerns about whether White House, Department of Justice or other executive branch officials are trying to prevent a legitimate whistleblower complaint from reaching its intended recipient, the Congress, in order to cover up serious misconduct.”

In a letter to Maguire accompanying the subpoena, Schiff said: “The Committee can only conclude, based on this remarkable confluence of factors, that the serious misconduct at issue involves the [president] of the United States and/or other senior White House or [administration] officials.”

Schiff added that the complaint was filed a month ago, but his committee has not received it for review, “in violation of the law” and had only learned of its existence this past Monday. The lawmaker said Maguire told the committee in a letter that he was withholding the complaint from the committee “because, in part, it involves confidentially and potentially privileged communications by persons outside the intelligence community.”

A senior intelligence official told The Associated Press the intelligence director’s office had received the subpoena and was reviewing it, and said Maguire is committed to upholding whistleblower protections

“It [is] of vital importance that intelligence officials have a lawful and protected means of bringing misconduct to the attention of Congress and the public,” Schiff said in his statement. “By withholding a credible whistleblower complaint that potentially deals with executive branch wrongdoing, the Director is in violation of the applicable statute and has made itself a party to the concealment of potentially serious misconduct.”

The intelligence panel is conducting a review of former special counsel Robert Mueller’s report on Russian interference in the 2016 election and obstruction of justice by the White House. The committee is also investigating President Donald Trump’s finances.